The only reason the Org would want to stop its members from exposing themselves to any ideas contradicting their policies/doctrine would be to prevent questions being asked. Warning of liars simply doesn't cut it because much of what is out there are NOT lies. If they merely discouraged members from outside research I wouldn't necessarily be lconvinced they were fearful of growing scutiny and exposure but there is ALWAYS a threat of apostasy involved where outside questioning is involved. As far as keeping people away from enemy propaganda goes, the threat of treason is the oldest tactic in the book and you're either blind, stupid, deaf or a child with your fingers jammed into your ears stomping your feet while yelling at the top of the lungs "Not true! Not true! Not true!" if you don't get that. Then again, it's more likely you're just ignoring the obvious because without holding onto the Disneyland dream your life has zero meaning or purpose, in which case I don't feel sorry for you, only embarrassed you're a member of my species.